linux-kernel - [PATCH] tick-common: touch watchdog for every cpus when system resume

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Date:   Fri, 10 Jan 2020 16:39:02 +0800
From:   Chunyan Zhang <zhang.lyra@...il.com>
To:     Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Chunyan Zhang <zhang.lyra@...il.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>
Subject: [PATCH] tick-common: touch watchdog for every cpus when system resume

In the function tick_unfreeze(), it would resume timekeeping for the
first cpu, and for other cpus it does local tick resume only, not
to touch watchdog which is per-cpu as well.

This probably is not the problem for suspend to ram, but for suspend
to idle is. Since watchdog would be setup for each unplugged cores when
plugging during resume and would be touched in its setup process. But for
suspend to idle the system wouldn't unplug/plug cores, so we should
touch watchdog once resume from s2idle to avoid 'soft lockup' warnings
due to timeout detected by watchdog.

Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
---
 kernel/time/tick-common.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 59225b484e4e..7e5d3524e924 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/hrtimer.h>
 #include <linux/interrupt.h>
+#include <linux/nmi.h>
 #include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/sched.h>
@@ -558,6 +559,7 @@ void tick_unfreeze(void)
 		trace_suspend_resume(TPS("timekeeping_freeze"),
 				     smp_processor_id(), false);
 	} else {
+		touch_softlockup_watchdog();
 		tick_resume_local();
 	}

-- 
2.20.1